New Zealand Prime Minister John Key is downplaying reports of bad behaviour by Kiwis in London as doubts are cast on claims by an expatriate Kiwi.

Former Wellingtonian Dylan Clements, a London travel agent, has filed a complaint with New Zealand High Commissioner Derek Leask saying the drunken antics of Waitangi Day pub crawlers brought “great shame” on New Zealand.

Mr Key says it’s great that New Zealanders around the world celebrate Waitangi Day.

“It’s no great surprise to me that New Zealanders in London are doing that by having a few beers,” he said on Tuesday.

“We would hope they wouldn’t get out of control but I don’t think we should over-egg this thing – New Zealanders are well known for having a pretty good time in London.”

Mr Clements says he saw pub crawlers urinating and vomiting on famous landmarks, including Westminster Abbey and the Jewel Tower, and exposing themselves indecently on the street.